Method of forming printing plates



Feb. 22, 1949. B. F. TERRY 2,452,570

' METHOD OF FORMING PRINTING PLATES I Filed Feb. 3, 1944 IN VEN TOR.

BBENNETT F2 TERRY Patented Feb. 22, 1949 UNITED STATES 2 Claims.

This invention relates to improvements in method of forming a printing plate and has for a principal object the formation of printing plates from silver halide emulsions after the latter are exposed, developed, fixed and tanned. The tanning hardens and shrinks the emulsions in areas where the exposed silver remains and the plate is formed to physically conform to the highs (unshrunken portions), and the lows (shrunken portions) of said emulsions.

Another object of the invention is the provision of a printing plate from an exposed, developed, fixed, and hardened silver halide emulsion by taking an impression of the surface of said emulsion with a wax-like or other formable and settable material, insuring that the surface of the latter bearing the impression is electrically conductive, and electro-depositing a film of copper or other metal onsaid electrically conductive surface.

A further object of the invention is the formation of a printing plate from an exposed, developed, fixedand hardened film carrying a silver halideemulsion, by taking an impression of the surface of said emulsion with a formable and setrable material and applying a layer of molten metal to said impression and allowing said metal to cool and set, thereby forming a metallic replica of the image on said film.

A still further object of the invention is the provision of a printing plate from a film having a silver halide emulsion thereon after the same is exposed, developed, fixed, washed, and hardened, by applying a wax-like material to the surface of the emulsion and applying pressure, thereby causing the surface of the wax in contact with the film to conform to the highs and lows in the surface of the emulsion, insuring that the surface of the wax-like material is electrically conductive, and thereafter electro-depositing a film of copper or other metal to said conductive surface. Other objects andadvantages will-be apparent to those skilled in the art.

Referring to the drawings, which are given by way of example to illustrate the invention:

Fig. 1 is a fragmentary enlarged cross-section of a film carrying a silver halide emulsion;

Fig. 2 is a sectional elevation of the film shown in Fig 1 after the emulsion has been exposed, developed, fixed, washed, and tanned.

Fig. 3 is a sectional elevation, like Fig. 2, except that a sheet of wax is being positioned on its tanned surface.

Fig. 4 is a view similar to Fig. 3 except that the wax is in contact with the surface of the emulsion 5 and pressure is applied to the upper surface of the wax, thereby causing it to conform to the surface of the emulsion;

Fig. 5 is a sectional elevation of the wax after it has been separated from the surface of the emulsion and has had its conforming surface made electrically conductive;

Fig. 6 is a sectional view of the wax after it has been removed from the electro-plating bath and has a deposit of copper on its conductive surface; and

Fig. 7 is a sectional view of the copper after the wax has been removed therefrom and a backing of type metal or the like has been applied thereto to form a printing plate.

This invention is a continuation in part of my copending application Serial No. 391,101, filed April 30, 1941, now Patent No. 2,384,857, dated September 18, 1945, for Printing apparatus and methods of preparing and using the same. In said copending application the film, or carrier, has one of its surfaces toothed, roughened or grained and a thin layer of light sensitive emulsion is applied to the toothed surface of the carrier. Due to the fact that the emulsion is thin, the outer surface of the emulsion conforms to the toothed surface of the carrier and is, consequently, also toothed. When the plate is exposed and developed, and subsequently tanned, the portions of the emulsion containing metallic silver are hardened and the highlights remain relatively soft and retain their toothed surface which facilitates the dispersal of aqueous repellent, the latter being adsorbed and absorbed by the comparatively soft gelatine. Figure 1 represents applicants film before exposure, and Figure 2 represents the same film after it has been exposed, developed, fixed and tanned.

Referring first to Fig. 1, the film 2B is shown as having a toothed, roughened or grained surface 2 l and the emulsion 22 applied to the toothed, roughened or grained surface also has its outer surface toothed, roughened or grained to conform to the surface 2|.

After the film has been exposed, developed and fixed it is tanned, for example, by treating it in a solution including the following chemicals in substantially the following proportions:

( 1) Copper sulphate, 10% solution, 8 oz.

(2) Potassium bromide, 10% solution, 8 oz.

(3) Potassium bi-chromate, 20% solution, 2 oz. (4) Sulphuric acid, 10% solution, 20 drops. (These are the proportions described in my application referred to herein above.) As shown in Fig. 2, the portions or areas 23 where the exposed silver remains, are shrunken and hardened. Consequently they lie substantially below the outer surface of the emulsion, the distance below depending upon the nature of the emulsion and the thickness. The highs or unshrunken portions 25 of the emulsion having toothed, roughened or grained surfaces forms a printing plate from which impressions may directly or by means of offset be obtained. It will be understood that the film shown in Fig. 2 is a negative of the copy and that it is desired to form a plate thereon for type high printing. In order to make a printing 'plate from the negative shown in Fig. 2, a

sheet of wax-like formable material 25 is applied to the surface of the emulsion 22 and an even pressure is applied to the upper surface 26 of this wax-like material as shown in Fig. 4, thereby causing its lower surface 21 to conform to the surface of the emulsion 22, with the result that all of the highs and lows of the surface of the negative are impressed in the wax in reverse order. The wax 25 is then removed from the negative 29, and its surface 27 is coated with a conductive material, such as plumbago or other electrically conductive material, or the electrically conductive material may be mixed with the wax beforehand. The wax sheet 25 is then placed in the electrolyte of a plating bath, for example, a copper plating solution and its conductive surface 21 is connected to a source of current and thereby a deposit of copper .28 is appliedto the surface 21 of the wax sheet 25. The wax sheet 25 is then removed and the back of the copper plate 28 is thoroughly cleaned and molten type metal or any other suitable backing may be applied to take the place of the wax 25, with the result that a printing plate, such as that shown in Fig. 7 is formed, said plate consisting of a copper face 28 with a suitable backing of type metal or the like 29, which may be mounted for use in the usual manner.

The term tanned emulsion or any reference to the emulsion after the same has been tanned, as used in this specification and the appended claims, is to be taken to mean the tanned image which was obtained as a result of tanning the image after the unexposed silver halide has been removed .by means of the clearing-fixing bath.

Although I have herein shown and described, 'by way of example, a method of carrying out the invention, it is obvious that other changes in the arrangements herein shown and described may be made by those skilled in the art without departing from the spirit of the invention as definedin the annexed claims.

What I claim is:

1. The method of forming a rinting plate consisting of the step of processing the surface of a carrier to make it toothed, roughened or grained, the stepof coating said surface with a thin silver halide emulsion, whereby the outer surface of said emulsion conforms to said toothed, roughened or grained surface, the further step of photographing the matter to be reproduced on said silver halide emulsion, and developing, fixing, and forming in said emulsion a tanned image of said matter, treating a wax material to make it electrically conductive, said material being adapted to set, the step of applying said material to the surface of said tanned emulsion under pressure and allowing it to set, the step of removing said material from said emulsion after the same has been set, the step of electro-depositing a metallic layer on the surface bearing said impression, and the final steps of removing said layer from said material and backing and mounting the same.

2. The method of forming a printing plate consisting of the step of processing the outer surface of a carrier to make it toothed, roughened or grained, the step of applying a thin layer of a silver halide emulsion on the outer surface of said carrier, whereby the outer surface of said emulsion is toothed, roughened, or grained, the step of transferring an image of the matter to be reproduced by means of light to said silver halide emulsion, the steps of developing, fixing, and tanning the exposed emulsion whereby the developed image is hardened and shrunken by the action of the tanning solution, the step of treating a waxy material to make it electrically conductive, said material adapted to set, the step of applying said material to the surface of said tanned emulsion, applying pressure thereto and allowing it to set, the step of removing the then set material from said emulsion electro-depositing a layer of metallic copper on the contact surface of said material, and the final steps of removing said layer from said material and backing and mounting the same.

BENNETT F. TERRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS.

Number Name Date 242,414 Guillebaud May 31, 1881 295,657 McIndoe et al Mar. 25, 1884 865,719 Murray Sept. 10, 1907 1,311,275 Harrison July 29, 1919 1,811,971 Sauer June 30, 1931 1,973,782 Rosenqvist Sept. 18, 1934 1,991,009 Browne et a1 Feb. 12, 1935 2,019,590 Westra Nov. 5, 1935 2,085,048 Schultz June 29, 1937 2,384,113 Miller Sept. 8, 1945 2,384,857 Terry Sept. 18, 1945 FOREIGN PATENTS Number Country Date 2,373 Great Britain 1854 OTHER REFERENCES Electrodeposition of Metals, by G. Langbein, 9th edition, 1924. 

